Ivermectin anti-parasite drug molecule. Computer illustration showing the structure of a molecule of the anti-parasitic drug ivermectin. Atoms are represented as spheres and are colour-coded: carbon (large, white), hydrogen (small, white) and oxygen (red). This drug is used as a broad-spectrum treatment for parasitic worms. Atoms are represented as spheres and are colour-coded: carbon (grey), hydrogen (white) and oxygen (red).